Grinding machine with means for compensating for grinding wheel wear



Nov. 17, 1964 G. D. BEHLEN 3,157,006

GRINDING MACHINE WITH MEANS FOR COMPENSATING FOR GRINDING WHEEL WEAR Filed Sept. 10, 1963 2 Sheets-Sheet 1 INVENTOR GEORGE DI BEH LEN,

25M, Him

I ATTORNEYS,

Nov. 17,1964 (5 D. BEHLEN 3,157,006

GRINDING MACHINENWITH MEANS FOR COMPENSATING FOR GRINDING WHEEL WEAR Filed Sept. 10, 1965 2 Sheets-Sheet 2 INVENTOR. GEORGE D. BEHLEN,

BY W,M,u:.m wit ATTORNEYS.

United States Patent GRlNDlNG MAG-ZINE WETH ll IEANS FUR (10M- PENSATEN G FUR GRINDlNG WHEEL WEAR George Dewey Behlen, .Lineinnatl, Qhio, assignor to The United States Electrical ToolCo South Fort Mitchell,

Ky, a corporation or Uhio Fii'ed'Sept. 10, 1963, Ser. No. 307,932

' 12 Claims. (Qt. 51-1345) This invention resides in the provision of means for insuring, in a grinding machine, that the grinding wheel will be rotatedat substantially its rated speed throughout substantially the full life of the grinding wheel, and is a continuation-impart of my co-pending application, Serial No. 226,307, now abandoned.

Various kinds and sizes of grinding wheels are employed in grinding machines adapted to rotate the grinding wheels in accordance with the type and size of the wheel and the kind of job to be performed. A given wheel, for a given job, will have a rated and maximum speed at which it should be rotated in order for it to be most effective. As these wheels are worn down by use, however, the peripheral speed of the grinding surface of the grinding wheel, in the absence of any adjustment, will be considerably lessened. In addition, as the wheel becomes worn, it is necessary to make adjustments in the position of the tool and hand rest. if the operator forgets or refuses to adjust the hand rest, the chances for injury, and for inferior work, are increased as the space between the hand rest and grinding wheel increases as the wheel is diminished through use.

A very important object of this invention is to provide means which make it possible, in convenient and positive manner, to keep the peripheral speed of the grinding wheel at substantially its maximum, rated speed throughout substantially the full, useful life of the grinding wheel.

Other objects and advantages of the invention will become apparent to those skilled in the art from the following description of the invention, keeping the above remarks in mind, and with reference to the accompanying drawings, in which drawings like numerals are employed to designate like parts throughout, and in which:

FIGURE 1 is a fragmentary side elevation of a grinding machine to which the instant invention has been applied,

FIGURE 2 is a section taken on the line 2-2 of PEG- UR FIGURE 3 is a section, with parts broken away and parts removed, taken on the line 3-3 of FIGURE 2,

FIGURE 4 is a cross-sectional view of my invention, with parts broken away, shown in another embodiment, and

FIGURE 5 is a partial sectional view similar to FIG- UB5 2, but showing the embodiment of FIGURE 4.

Briefly, the invention may be generally described in the following manner. The grinding machine includes a grinding wheel shaft on which the grinding wheel is mounted and a motor for rotating this shaft. A pulley of fixed diameter is positioned on the drive shaft of the motor. A pulley of variable diameter is positioned on the grinding wheel shaft. The grinding wheel shaft is mounted in the machine so as to be movable with respect to the motor. The tool and hand rest has a fixed position in the machine. The pulleys for the motor and grinding wheel shaft are selected as to size in accordance with the characteristics of the motor and the desired speed for the peripheral surface of the grinding wheelwhen new. initially the belt from the motor pulley to the grinding wheel pulley will ride at the outer extremity of the variable pulley which is mounted on the grinding wheel shaft. The slidable assembly which includes the grinding wheel shaft is engaged by a screw operated by a hand wheel positioned in the machine. As the grinding wheel wears,

3,15 7,006 Patented Nov. 17, 1964 the operator will move the grinding wheel shaft and assembly, by turning the hand wheel just mentioned, away from the motor. This results in the belt from the motor pulley to the variable pulley riding lower in the variable pulley, thus imparting increased speed to the rotationof the grinding wheel shaft. This increased speed of the grinding wheel shaft will compensate for the reduced peripheral speed of the grinding wheel itself, which reduced speed is occasioned by the reduction in the diameter of the wheel due to wear. In this manner the wheel is constantly brought towards the fixed hand rest so as to maint h spacing t ereb twe n substantial y he sa while at the same time the effective peripheral speed of the grinding wheel is maintained substantially constant.

Referring now to the drawings, the invention will be described in greater detail. A grinding machine is generally indicated at It This machine includes the bed 11. A suitable, conventional motor 12 is mounted on the bed 11. A fixed diameter pulley 13 is mounted on the drive Shaft 14 or the motor 12.

The driven, grinding wheel shaft 15 is mounted in suitable bearings so within the housing 17. A grinding wheel 18 is fixed on one end of the grinding wheel shaft 15 within the guard housing 19 which is secured to the bed ll of the machine. A variable diameter pulley ii} of conventional design is mounted on the other end of the grinding wheel shaft l5. It will be undrstood that the two halves of the pulley Ella and Ztlb are movable and normally urged towards one another by springs Ztld and 200 respectively. A belt 21 engages the fixed pulley 13 on the drive shaft motor 14 and the variable diameter pulley 29 on the grinding wheel shaft 15. The sizes of the pulleys 13 and 2%) will be selected in accordance with the characteristi cs of the motor 122 and grinding wheel 18 so that initially the position of the grinding wheel shaft 15 with respect to the motor 12 and its shaft 14 is such that the belt 21 will ride at the extreme, outer periphery of the pulley 2%, in which position the peripheral speed of the grinding wheel 13 will be that desired for maximum efficiency. The conventional, variable diameter pulley 20 is such that as it and the shaft 15 are moved away from the motor shaft 14, the two halves 291; and 2% of the pulley will move away from one another in opposition to their re spective springs Zlld and Zllc with the result that the belt 21 will move from the extreme, outer periphery of the pulley 26 to a position between the pulley haves which is closer to the grinding wheel shaft 15. It will be obvious to those skilled in the art that when the belt 21 moves within the variable diameter pulley 2t: to a position closer to the grinding wheel shaft 15, the speed of rotation of this shaft will be increased. l l

The main housing 1'7 for the grinding wheel shaft 15 includes a base 23 which rides in the pair of tracks 23 formed in the members 24 mounted on the base plate 11. Reinforcing members 25 extend from the plate 22 to the housing proper 17, In the position shown in FIGURE 2 wherein the pulleys 13, and 20 have been selected for a particular, new grinding wheel 18, the base plate 22 abuts the stop 26 and the belt 21 rides at the extreme, outer Periphery o th a et i The means for moving the housing block 17 22 in the tracks 23 defined by the members 24 located on the ma chine bed 11. include the bearing block 27, located at the end of the track 23 opposite the, slide stop 26. This block 2? is securely locatedon the bed 11. A threaded shaft or screw 28 is suitably journaled in the bearing block 27,. This screw 28. may be rotated by means of the hand wheel 291 fixed to the outerend thereof. This screw 28 engages within the depending tubular lug 3b, which is. fixed to the bottom of the slide block 2 2 of the main housing 17 for the grinding wheel shaft 15. The arrangement among the parts 28, 29 and 3t} is such that rotation of the hand .with legs. 32 adapted to ride in the tracks 23.

wheel 29 will cause the screw 28 to be rotated, whereby the lug 30 and slide 22' will be moved along the tracks 23. Also mounted in fixed position on the machine it is the tool and hand rest 31. Normally, assuming that a new grinding Wheel 18 is about to be used and assuming also that the pulleys 13 and 2d are of the proper size for such wheel, the parts will initially be in the positions indicated in FIGURES 1 and 2. The slide block 22, therefore, will be in the tracks 23 against the stop 26 and the outer periphery of the grinding wheel 18 will be closely adjacent the tool and hand rest 31.

In operation, the invention will function as follows. As the grinding wheel 18 becomes worn, the working periphery thereof will be lessened. This has the effect of slowing down the operative face or periphery of this wheel. As such wear occurs, however, the operator will rotate the hand wheel 29 so as to actuate the screw 28 whereby to cause the slide block 22, by reason of the screw 28 operating within the lug 30 which is fixed to this block 22, to slide along the tracks 23 away from the stop 26 and towards the bearing block 27. This causes the grinding wheel shaft 15 to be moved away from the motor shaft 14. The elongated hub 1% of fixed guard housing 19 (see FIGURES l and 2) permits this movement of the shaft 15. As this occurs the halves of the variable pulley 24) will separate to some extent, thus permitting the belt 21 to ride Within the pulley 2t) closer to V the shaft 15. In this new position of the belt 21 in the pulley 20, greater speed is transmitted from the motor 12 to the grinding wheel shaft 15. Greater speed of rotation of this shaft 15, of course, results in the grinding wheel 18 being revolved at a higher rate of speed also. This higher rate of speed imparted to the grinding wheel 18 compensates for the fact that the periphery thereof has been lessened by wear. In this manner, therefore, the actual speed of the working face of the grinding wheel 18 may be kept substantially constant, the space between this working face of the grinding wheel and the hand and tool rest 31 may also be kept substantially constant, and the entire grinding wheel will also maintain its proper space relationship to the fixed guard 19.

In FIGURES 4 and 5 I have shown-a modification oi has an original diameter of 30 inches, and through extensive use is reduced to a diamether of 15 inches, the first embodiment shown and described does not readily lend itself to use with these larger grinding wheels. To adapt my invention for such use, I provide means for moving the motor 12 with its shaft 14 and drive pulley 13 in the same direction in which the grinding shaft 15 is moved, but at a considerably slower rate. In terms of my original example, a 15 inch reduction in the diameter of the grinding wheel is equal to a 7 /2 inch reduction in its radius. To keep the edge of the grinding wheel up adjacent to the tool rest 31 it is therefore necessary to move the grinding wheel shaft gradually in the direction of the tool rest a total of 7 /2 inches. I have found that in such circumstance the gradual movement of the motor and its shaft about 4 /2 inches in the same direction during the movement of the grinding wheel shaft will produce desirable operating qualities, but these figures and propor- I' tions are exemplary only, anddo not in any way limit my invention;

Referring now more specifically to FIGURES 4 and 5, the members 24 and'the tracks 23 extend all the way acrossthe bed 11. The motor 12 must now be equipped I then provide a threaded shaft or screw 33, on which the pitch of the threads is somewhat lower than the pitch on the threaded shaftor screw 28. I then provide a coupling -member suchfas that shown at 34which will join the two screws 28 and 33. The member 34 maybe of any Well knownand conventional design. The screw 33 will spirit thereof.

engage the depending lug 35 on the bottom of the motor 12. As will now be understood, through rotation of the hand crank 29, the threaded screw 28, and the threaded screw 33, I move both the grinding shaft 15 and the motor 12 in the same direction but at different speeds. By proper adjustment of the proportion and pitch of the two screws, along with the correct relationships among the sizes of the grinding wheel, the variable diameter grinding wheel shaft pulley, and the fixed diameter drive pulley on the motor drive shaft, I can regulate the relative movement of the grinding shaft and the motor, and thereby bring about desired optimum operation of the device.

Again referring to the example in which a grinding wheel 18 having an original diameter of 30 inches is employed, the variable diameter pulley 2% will normally have an initial working diameter of 12 inches. When the grinding wheel has been reduced by wear to a diameter of 15 inches, the correct working diameter of the pulley 20 is six inches. This means that while the shaft 15 had to be moved seven and one-half inches closer to the tool and hand rest 31, the belt 21 had to be moved, within the halves of the variable diameter pulley 20, only three inches'closer to the shaft 15. It is necessary, therefore, under these conditions to move the motor 4 /2 inches closer to the shaft 15 during the time this shaft 15 is moved 7 /2 inches closer to the rest 31 in order that the belt 21 is moved only three inches (within the pulley 20) closer to the shaft 15. This as stated above, is accomplished by selecting screws 28 and 33 of proper pitches.

It is believed that the invention has been fully and clearly described in the foregoing passages. It is to be understood that while the invention has been shown as embodied in certain arrangements and structures, such showing is'exemplary only, and the certain arrangements and structures are not to be considered a limitation on the invention except insofar as they are specifically set forth in the subjoined claims. Furthermore, it will be apparent to those skilled in the art that modifications may be made in the invention without departing from the scope and Having thus described the invention, what is claimed as new and what it is desired to protect by United States Letters Patent is:

a 1. In a grinding machine having a motor, a drive shaft driven by said motor, a grinding wheel shaft, a grinding wheel fixed on said grinding wheel shaft, pulleys fixed on said drive shaft and on said grinding wheel shaft respectively, and a belt connecting said pulleys so as to transmit power from one to the other, the improvement which comprises: said pulley on said drive shaft being of fixed diameter, said pulley' on said grinding wheel shaft being, of variable diameter, and means to move said grinding wheel shaft from said drive shaft as said grinding wheel becomes worn, so that said belt moves from the outer periphery of said variable diameter pulley towards the center thereof, whereby to speed up rotation of said grinding wheel shaft and grinding Wheel to compensate for the worn grinding Wheel.

2. In a grinding machine according to claim 1, a fixed guard housing for said grinding wheel, whereby movement of said grinding wheel shaft from said drive shaft serves to maintain the spaced relationshipbetween said guard housing and said grinding wheel as said grinding wheel becomes worn. v

3. A. grinding machine 'comprising a base, a motor mounted on said base, said motor having a drive shaft, a housing slidably mounted on said base, a grinding wheel shaft rotatably mounted in said housing, a grinding wheel on said grinding wheelshaft, a fixed diameter pulley on said drive shaft, a variable diameter pulley on said grinding Wheel shaft, a belt connecting said pulleys so that said variable diameter pulley is driven by said fixed diameter pulley, and means to slide said housing away from said motor'so as to move said belt within said.

variable diameter pulley to a position closer to said grinding Wheel shaft, whereby to increase the speed of rotation of said grinding wheel.

4. The machine of claim 3 in which said housing is mounted on a slide block, a pair of tracks on which said slide block is slidable, and said means to slide said housing comprising a threaded lug on said slide block, a bearing block fixed on said base, a screw rotatable in said bearing block, said screw operatively engaging said lug, and a hand wheel on said screw by means of which said screw is rotated.

5. A grinding machine comprising a base, a motor mounted on said base, said motor having a drive shaft, a tool rest fixed on said base, a housing slidably mounted on said base between said motor and said tool rest, a grinding wheel shaft rotatably mounted in said housing, a grinding wheel on said grinding wheel shaft, a fixed diameter pulley on said drive shaft, a variable diameter pulley on said grinding Wheel shaft, a belt connecting said pulleys so that said variable diameter pulley is driven by said fixed diameter pulley, and means to slide said housing away from said motor toward said tool rest so as to move said belt within said variable diameter pulley to a position closer to said grinding wheel shaft, whereby to increase the speed of rotation of said grinding wheel and whereby to bring said rinding wheel toward said tool rest.

6. The grinding machine of claim 5 including a guard housing fixed on said base for said grinding wheel, where by when said grinding wheel is brought toward said tool rest the space relationship between said guard housing and said grinding wheel is maintained.

7. A grinding machine comprising a base, a motor including a drive shaft slidably mounted on said base, a housing slidably mounted on said base, a grinding wheel shaft rotatably journaled in said housing, a grinding wheel on said grinding wheel shaft, 21 fixed diameter pulley on said drive shaft, a variable diameter pulley on said grinding wheel shaft, a belt connecting said pulleys so that said variable diameter pulley is driven by said fixed diameter pulley, means to slide said housing away from said motor so as to move said belt within said variable diameter pulley to a position closer to said grinding wheel shaft whereby to increase the speed of rotation of said grinding wheel, and means for sliding said motor in the same direction as said housing but at a slower rate.

8. The device claimed in claim 7, wherein said means to slide said housing away from said motor comprises a first threaded lug on said housing, a bearing block fixed on said base, a first screw rotatable in said bearing block and operatively engaging said lug, and a hand wheel on said screw by means of which the screw is rotated and wherein the means for sliding said motor in the same direction as the housing but at a slower rate comprises a second threaded lug located on said motor, a second screw coupled to said first screw and operatively engaging said second threaded lug, said second screw having a lower pitch than said first screw.

9. The grinding machine of claim 7 including a tool rest fixed on said base, whereby said grinding wheel is brought towards said tool rest when the said means for sliding said housing and said motor are actuated. 10. The grinding machine of claim 7 including a guard housing fixed on said base for said grinding wheel, whereby the space relationship between said guard housing and said griding wheel is maintained when the means for sliding said housing and said motor are actuated.

ll. in a grinding machine including a. motor having a drive shaft, grinding wheel shaft, a grinding wheel fixed on said grinding wheel shaft, pulleys fired on said drive shaft and on said grinding wheel shaft respectively, and a belt connecting said pulleys so as to transmit power from one to the other, the improvement which comprises: said pulley on said drive shaft being of fixed diameter, said pulley on said grinding wheel shaft being of variable diameter, means to move said grinding wheel shaft away from said drive shaft as said grinding wheel becomes worn, so that said belt moves from the outer periphery of said variable diameter pulley toward the center thereof, whereby to speed up rotation of said grinding wheel to compensate for the reduction in size due to wear, and means to move said motor in the same direction as said grinding wheel shaft but at a slower rate.

12. A grinding machine comprising a base, a motor including a drive shaft slidably mounted on said base, a housing slidably mounted on said base, a grinding wheel shaft rotatably journaled in said housing, a grinding wheel on said grinding wheel shaft, a guard housing fixed on said base for said grinding wheel and having a predetermined spaced relationship from said grinding wheel, a tool rest fixed on said base and having a predetermined spaced relationship from said grinding wheel, a fixed diameter pulley on said drive shaft, a variable diameter pulley on said grinding Wheel shaft, a belt connecting said pulleys so that said variable diameter pulley is driven by said fixed diameter pulley, means to slide said housing away from said motor so as to move said belt within said variable diameter pulley to a position closer to said grinding wheel shaft whereby to increase the speed of rotation of said grinding wheel shaft, and means for sliding said motor in the same direction as said housing but at a slower rate, whereby when said means for sliding said housing and said motor are actuated so as to increase the speed of rotation of said grinding wheel to compensate for wear of said grinding wheel, the said space relationships between said guard housing and said grinding wheel, and between said tool rest and said grinding wheel, are maintained.

References Cited in the file of this patent UNITED STATES PATENTS 2,003,495 Ritz June 4, 1935 FOREIGN PATENTS 1,052,587 France Mar. 19, 1952 

1. IN A GRINDING MACHINE HAVING A MOTOR, A DRIVE SHAFT DRIVEN BY SAID MOTOR, A GRINDING WHEEL SHAFT, A GRINDING WHEEL FIXED ON SAID GRINDING WHEEL SHAFT, PULLEYS FIXED ON SAID DRIVE SHAFT AND ON SAID GRINDING WHEEL SHAFT RESPECTIVELY, AND A BELT CONNECTING SAID PULLEYS SO AS TO TRANSMIT POWER FROM ONE TO THE OTHER, THE IMPROVEMENT WHICH COMPRISES: SAID PULLEY ON SAID GRINDING WHEEL OF FIXED DIAMETER, SAID PULLEY ON SAID GRINDING WHEEL SHAFT BEING OF VARIABLE DIAMETER, AND MEANS TO MOVE SAID GRINDING WHEEL SHAFT FROM SAID DRIVE SHAFT AS SAID GRINDING WHEEL BECOMES WORN, SO THAT SAID BELT MOVES FROM THE OUTER PERIPHERY OF SAID VARIABLE DIAMETER PULLEY TOWARDS THE CENTER THEREOF, WHEREBY TO SPEED UP ROTATION OF SAID GRINDING WHEEL SHAFT AND GRINDING WHEEL TO COMPENSATE FOR THE WORN GRINDING WHEEL. 